is - oshawaapp.oshawa.ca/agendas/development_services/2010/08... · the problem at 1532 skyview was...

S. 1 4(1), Municipal Freedom of Information and Protecfion of Privacy Act

August 23,2010

Mayor John Gray and The Development Services Committee 50 Centre Street South Oshawa, O N L1H 327

Dear Mayor Gray and Members of the Development Services Committee:

Despite my repeated pleas for assistance during a period of several years, little to no attention has been paid to me and to the problem that exists with a home that the City allowed to be built and sold. My family has been burdened with replacement costs of basement carpeting and flooring due to the constant backup of water. I have attached documentation that outlines in detail the situation a t my home.

Date July 25,2002

June 27,2006

June 13,2007

D.G. Biddle & Assoc. Writes City of Oshawa

Letter to Councillor John Neal

Report to Development Services Committee

Comments "The sanitary and foundation drainage sewers servicing the dwellings are all below the level of the basement floor and generally will intercept ground water flows." Talked to Councillor Neal on March 10, 2006 and explained flooding problem twice a year due to calcium carbonate buildup. Sent followup letter on June 27, 2006; however, no response from Councillor Neal. I respectfully request that this report be reviewed in its entirety. Throughout the report reference is made to "Clearsky Ave", the potential problems and suggested solutions. The report clearly identifies that problems will occur and will need to be addressed.

Date July 20,2008

July 26,2008

April 26,2010

June 29,2010

Spoke to: Mayor John Gray

Call to Service Oshawa Spoke with "Jennifer"

Letter to D.G. Biddle & Associates

Comments Sent followup letter July 29, 2008, stating that the City of Oshawa corrected the water problem at 1532 Skyview in Oshawa. Their problem was identical to the situation at 597 Clearsky. The City resolved their water problem in 2006. Why did the City of Oshawa fix their problem, but reject fixing my home? At the time I sought assistance, my basement was completely flooded. Mayor John Gray visited my home to assess the basement ' situation. Although there was a commitment to respond and assist, no assistance has been provided. Opened Case #34166 I was advised that information would be forwarded to the Public Works Department. I was referred to "Chris" in Engineering. He advised that Engineering would probably not be involved. I then called Region of Durham and spoke to "Pearl". She advised that she would forward the communique to her Supervisor. Acting Supervisor called to advise cleanout would occur. Supervisor on vacation. Nothing has happened to date. Letter outlines events and concerns. Although I have visited Mr. Biddle's office on several occasions, no response or action has been forthcoming.

Following are just a few of the dates where extensive flooding of the basement has occurred: July 22, 2004; April 26 and November 26, 2005; March 23, 2006; July 20, 2008; May 1, 2010. Each time flooding occurs, the City is contacted. Although the City has attempted to clear the pipe, calcium carbonate continues to collect (please see attached photos). The size of the pipe opening therefore is diminishing due to the extensive buildup of this material. As you can appreciate, each time flooding occurs, hours of cleanup are required.

Recently, I happened to answer the door. Mayor John Gray was canvassing for support for the upcoming election. Once again, I advised Mayor Gray of-the situation and he suggested a meeting in his office on August 23,2010.

I have repeatedly telephoned and I have visited the City of Oshawa and Biddle and Associates; I have contacted the builder on several occasions. Not one person has helped to resolve this overwhelming problem.

I have to ask how any one of you would handle the situation I find myself in after purchasing this home. I have been more than patient and I have been persistent. If the City of Oshawa can approve the building of a home and yet recognize that there could be future problems, then the City of Oshawa, D.G. Biddle &Associates and the builder are responsible to ensure that a homeowner's investment is protected. In my opinion, it was the responsibility of the builder, the engineering firm and the City of Oshawa to ensure that problems that I am experiencing would not exist once the house was completed and put on the market for sale.

I am originally from the Ukraine. I have received assistance to write this letter. As the problem at 1532 Skyview was resolved within a short period of time, I have to wonder if I am being discriminated against as I sometimes have difficulty finding the proper words to define the problems with this house.

This is a year of election. How do you think ratepayers would react if they heard my story through the media. There is an old adage: "let the buyer beware". I completely trusted everyone involved in the development of this area and the construction of this house. Inspections would have confirmed that the house could be put on the market for sale.

I t is my sincere request that this problem be resolved and fixed to my satisfaction immediately. According to the reports I have been able to obtain, there is a budget allocation to assist with the calcium carbonate problem in residential areas.

I am requesting that I receive in writing the steps that will be taken to ensure that the flooding of my basement will cease and that the calcium carbonate levels will be reduced. I t is my understanding that if the drainage around the outside of the house was changed, the problem with flooding would not occur within my basement.

I am unable to sell the house as I will not inflict this problem on another person. I t is my expectation that there will be a resolution to the problem. If there is no resolution, I will be seeking legal advice.

Yours truly, t *

Vaientyna Maksymlyuk 905-721-1703

and ,L L L .

Ruslan Maksymlyuk

*I i'i 5 LC;,

S. 14(1), Municipal Freedom of Information and Protection of Privacy Act

June 29,2010

Devan G. Biddle D.G. Biddle &Associates Ltd. 96 King Street E Oshawa, ON L1H 1 B

Dear Devan Biddle:

On May 18,2010, we discussed my concerns regarding a basement that has continued to flood for the past seven years.

In a July 25,2002, letter to the City, your firm acknowledged the water flow. Your letter states : "The sanitary and foundation drainage sewers servicing the dwellings are all below the level of the basement floor and generally will intercept ground water flows". Unfortunately, as you know, this has not been the case.

This matter has been discussed with the City of Oshawa, the builder of the home, and your firm. Each person/organization recognizes'that this is a serious problem, but not one person has taken the initiative to resolve this problem. In November 2008 Halminen attempted to fix the pipe in my house, but to date, the problem continues to exist. Although the city has agreed to clean the pipe each year, the calcium carbide buildup is so severe that it is not possible to incorporate a sump pump into the basement area. The pump would be severely clogged and would therefore be deemed inoperable.

It is hard for me to understand why no one will assist me with this problem. My family has been extremely patient. Recently, we had to replace the carpeting in the basement as, once again, the water built up to such an extent that the basement was flooded and carpeting destroyed.

Mayor John Gray visited my home and promised to assist. You visited my home and said you would get back to me. To date, there has been no action taken, nor have I had the courtesy of a response.

I am certain that if your family had to live in these conditions, you would be more than anxious to find a solution to this dreadful problem.

Once again, I am asking that you please determine what can be done and respond to me as soon as possible.

Yours very truly,

Ruslan @ ksymlyuk Valentyna Maksymlyuk

April 26,2010

Spoke to Jennifer, Service Oshawa, at 436-3311.

Opened Case # 34166 - will be forwarded to Public Works Department

Jennifer directed us to Chris in Engineering - he said Engineering would probably not be involved.

Called Region of Durham at 905-655-3344, and spoke to Pearl in Works. She said she would forward communiqu6 to her Supervisor.

FROM : Mckil Associatts PHONE NO. : 416 282 5148 Jul. 86 2810 12: 16PH PI

July 29. 2008

Mr. John Gray Mayor

Re: Foundation Drain File El400 Cammuni~y Services Department

Followi'ng our conversaion on Sunday, July 20,2008 regarding drainaye prublem in my house (597 Clearsky Ave., Oshawa), I am sending you the copy of the letter which i sent

7 ' I to the Dcpsnment Community Smices to the attention of Mike Molinary together with / I, i :/ -- J+r2,

the copy of wok ~ h a was done on my house on January 14.2008 by Prairie Plumbing \ ; P -i: Ltd.

In additlon to this 1 would like to let you know that there had been work done on 1532 Skyview Street in Oshawa back in August of 2006 by the City of Oshawil. And now they reject ro fix the same problem on my house (to change the pipe thu they broke and liabk for). That is why my house sits on water for two weeks now and no one wants to do anything about it. This is not fair.

I appreciate you considcraiion in this matter. f i

Valentyna Maksymlyuk

Community Services Department Public Works Services

REGSTERED MAIL & HAND DELIVERED

July 28, 2008

Ruslan Maksvmlvuk


RE: FOUNDATION DRAIN OUR FILE: E-1400

Thank you for meeting with us at your home on Wednesday, July 23, 2008 to inspect your foundation drain which appears to be blocked.

In 2007, Oshawa Ccuncil authorized a modest budget for a program to clean calcium carbonate from certain foundation drain collector systems. Pursuant to that program and in accordance with your "Permission to Enter Property" agreement ("Permission"), the City undertook certain "Work more particularly described in the Permission and which the City has determined to be the extent of what is practicable and reasonable for the purpose of the City's program. However, notwithstanding the City's efforts, it does not appear that its Work has cleared the blockage.

Accordingly, you should seek professional advice and assistance including that of a qualified plumber respecting the means of draining your foundation. The City will work reasonably with you and your advisors and contractors including to facilitate approvals where necessary to implement the corrective work. This FDC drain is an integral part of the drainage for your house foundation and we recommend that you act expeditiously to correct this problem to prevent future flooding and damage to your basement.

Mike Molinari, P.Eng Director Public Works Services

Copy: David Potts, City Solicitor Office of the City Manager David Watson Manager, Road & Depot Services, Community Services Department

The Corporation of the City of Oshawa, 50 Centre Street South, Cshawa, Ontario L1 H 327 Phone 905.725.7351 1-800.667-4292 Fax 905-436-5684 3 . i , www.oshawa.ca L j

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1.0 PURPOSE

The purpose of this report is to:

Date of Report:

June 13,2007 Date of Meeting: June 18,2007

Ward(s): *I1

To: Development Services Committee

From: Commissioner, Development Services Department

(a) Advise Council of the results of a detailed investigation into the formation of calcium carbonate within foundation drain systems in the City and;

(b) To recommend a Council policy for future management of the issue.

Item:

DS-07-174 File: E-6800 (9)

Report DS-06-76, dated March 1, 2006, advised Council of problems being experienced with the formation of calcium carbonate within foundation drain systems in the City. A copy of Report DS-06-76 appears as Attachment No. 1.

Subject: Calcium Carbonate Formation in Foundation Drain Collector Systems

PUBLIC REPORT

On March 20, 2006, in response to Report DS-06-76, Council passed the following resolution:

"That staff be authorized to retain Golder Associates Ltd. to investigate the cause of calcium carbonate formation in foundation drain collection systems at an estimated cost of $20,000 to be funded from 2006 operating contingency account."

Golder and Associates Ltd. ("Golder") has recently completed its study and a copy of its Conclusions and Recommendations is provided as Attachment No. 2. The full report is available for viewing in Engineering Services (ISt floor, Rundle Tower, attention Mike Sims).

2.0 RECOMMENDATION

That the Development Services Committee recommend to City Council:

1. That, based on Report DS-07-174 dated June 13, 2007 regarding the formation of calcium carbonate in foundation drains, Community Services initiate a regular cleaning program for foundation drain collector systems where calcium carbonate formation is known to be a problem.

2. That Community Services provide a cleaning service in 2007 for private property foundation drain laterals at a cost not to exceed $30,000 to be funded from the 2007 corporate contingency.

Report to the Development Item: 08-07-1 74 Services Committee (Continued) - 2 - Meeting Date: June 18,2007

3. That the Public Works Services 2008 budget submission be increased by $60,000 for the annual costs of cleaning private property foundation drain laterals.

4. That residents currently known to be affected by calcium carbonate in their private laterals be advised of Council's policy.

5. That the Development Services Department consult with the Building Industry Liaison Team (BILT) concerning the implementation of recommended measures to manage the formation of calcium carbonate in new developments and report back to Council should BILT have any major concerns.

3.0 EXECUTIVE SUMMARY

Golder was retained by the City in March 2006 to investigate the formation of calcium carbonate in foundation drain systems and throughout 2006 undertook a number of field investigations to determine the cause of the problem. Golder's final report concludes that the natural groundwater within the impacted area is saturated with calcium carbonate and as the water flows through certain materials found beneath the basement floor slabs of homes in the area, the pH of the groundwater changes and its' ability to maintain the calcium and carbonate in solution is reduced, thus resulting in precipitation of the material in the foundation drain systems.

Golder has recommended that the City: (a) institute a regular cleaning program for foundation drain collector mains and private property laterals where the formation of calcium carbonate is a problem; (b) Consider additional conditions of approval for new development to minimize the potential for future calcium carbonate problems.

4.0 INPUT FROM OTHER SOURCES

> Public Works Services (Community Services Department) has provided input to the report and supports the Recommendation.

> Finance Services (Corporate Services Department) has provided financial input to the report.

5.0 ANALYSIS

5.1 Golder Study

P As noted in Report DS-06-76 dated March 1, 2006 (see Attachment No. I) , calcium carbonate has been found in foundation drain systems in various parts of the City.

> A study by Golder has focused on the Wilson RoadIClearsky Avenue area where calcium carbonate formation is occurring on a fairly rapid basis.

Report to the Development Item: DS-07-174 Services Committee (Continued) - 3 - Meeting Date: June 18,2007

P Through 2006, Golder undertook field investigations in the WilsonIClearsky area as follows:

Borehole drilling and monitoring wells were installed at eleven (11) different locations. Groundwater level elevations were measured in each well in September 2006 and December 2006. Water samples were taken from 4 wells in September 2006 for chemistry analysis. Various soil materials typically used on construction projects were tested.

4 With the permission of the homeowners, boreholes were drilled through the basement floors of 4 homes on Clearsky Avenue and underlying material was collected for analysis.

> As a result of the investigation, Golder has concluded:

There are several areas within the area where the natural groundwater level is within approximately 1 metre of the ground surface. The foundation drains on a number of homes are therefore persistently at or below the groundwater surface. Groundwater within the area is saturated with respect to calcium carbonate. Golder believes this should be a fairly common occurrence in Oshawa as our soils are predominately derived from limestone. The pH of the groundwater was found to be in the 7.2 to 7.5 range. The pH of the gravel layer beneath basement floor slabs was in the 8.6-9.8 range. As groundwater flows through and interacts with the gravel beneath the floor slab, the pH of the groundwater rises and its ability to maintain calcium carbonate in solution is reduced, resulting in precipitation of the material in the drains. Material found beneath the floor slabs was an unwashed clear stone backfill, which is permitted by the Ontario Building Code.

> Golder has provided a series of recommendations to manage the issue in existing developments and minimize the potential for problems in future development.

> With respect to existing development, Golder has recommended that foundation drain systems (mains and private property laterals) be cleaned on a regular basis. Initially, it recommends that cleaning be carried out twice per year in the WilsonIClearsky area. Golder believes the frequency of cleaning will decline over time to a point where it may no longer be required. The time frame for this to occur cannot be determined. Cleaning in other areas may not need to be as frequent, dependent on the rate of calcium carbonate formation.

P With respect to future development, Golder recommends:

Chemical analysis should be performed on groundwater to assess the potential for calcium carbonate formation where groundwater is anticipated to be within the depth of influence of new foundation drains. The depth of footings below seasonal groundwater levels should be minimized as much as possible.


Where the potential for calcium carbonate formation is found, washed 19 mm clear stone should be used around new house footing drains and floor slabs. The lateral connection between streetline and the home footing drain should be increased from 100 mm to 150 mm to facilitate cleaning and inspection. Foundation Drain Collector (FDC) mains should be designed to minimize drop structures as the increased turbulence can also increase groundwater pH and cause subsequent calcium carbonate precipitation.

8 An inspection program should be put in place to examine FDC mains and lateral connections by the developer in order to monitor and manage any problems prior to assumption of the systems by the City.

5.2 Recommended Policy Measures

> In order to implement Golder's recommendations, a number of new measures are proposed.

> In developed areas where problems are being experienced, the following is recommended:

A regular cleaning program be performed on City FDC mains. Funding in the amount of $35,000 was approved in the Public Works 2007 operating budget for this purpose. Financial needs for this program will be assessed and determined on an annual basis through the budget process. A regular cleaning program be initiated on private property laterals where problems are identified. A few homes in the WilsonIClearsky area have received this service while the study was underway using a local plumbing company at a cost of $300 per cleaning for the service. Based on a preliminary assessment on the scope of work in areas around the City, an estimated $60,000 would be required annually to provide this service.

> The cleaning of laterals will require the City or its contractor to enter onto private property to perform the work as the clean-out for the FDC is located within the basement of each home. This is similar to services the Region of Durham provides private homeowners for sanitary service connections.

> While the City's past practice has been to view the cleaning of private FDC connections as a property owner responsibility, it is believed that the calcium carbonate issue is a unique circumstance in which the City should assist homeowners. Also, from a risk management perspective, providing the service to homeowners should also minimize claims against the City for damages to flooded basements arising from connections potentially impacted by calcium carbonate.


9 Within new development areas, the following is recommended:

8 The application of a standard condition of approval requiring a groundwater study and analysis that deals with the calcium carbonate issue. New clauses in the City's Development Agreements which require:

- The use of washed 19 mm clear stone on applicable building lots; - The use of 150 mm pipe for house laterals; - Annual inspection of FDC by the developer's engineer with all systems to be

videoed and cleaned prior to City assumption.

Revisions to the City's Engineering Design Criteria and associated policies to reflect the above noted requirements, and:

- Design of development to minimize the extent of building footing drains below the seasonal high groundwater table.

- Design of systems to minimize areas that would create turbulent flow.

> In addition to the above policy measures, a review will be undertaken by Development Services, in conjunction with Community Services, on the benefits of continuing to use a separate foundation drain collector system as opposed to the connection of foundation drain laterals to a deeper storm sewer. An annual testing and monitoring program will also be established.

6.0 FINANCIAL IMPLICATIONS

> The current estimated annual cost for cleaning City FDC system mains is $35,000. Funding was approved in the 2007 Public Works Services operating budget for this work.

> An additional estimated $60,000 is required to perform semi-annual cleaning of private house connections impacted by calcium carbonate formation. The 2007 Public Works Services budget did not include funding for the cleaning of private connections. If Council approves the undertaking of this work, the estimated cost of $30,000 for 2007 can be funded from the 2007 corporate contingency.

9 The 2007 budget for the corporate contingency is $187,900. As of June 21, 2007, approximately $171,500 has been expended or committed (this includes $30,000 for the cleaning of the private laterals), leaving approximately $16,400 in funding available for the remainder of 2007.

9 The 2008 budget for Public Works Services will need to be increased by $60,000 to fund the cleaning of private laterals if Council approves this report. It should be noted that the full scope of homes requiring cleaning is not fully known at this point in time and the overall budget for this service may need to change in the future.


7.0 RESPONSE TO THE COMMUNITY STRATEGIC PLAN

The investigation and recommended measures for the management and administration of the calcium carbonate formation in foundation drain collectors advances Goal A (A Vibrant, Strong and Progressive Community) and Goal C (A Caring and Responsive Community) of the City's Community Strategic Plan by promoting a positive City image and by ensuring accountability and effective City management.

Original Signed By

M. J. Sims, P. Eng., Director Engineering Services

Original Signed By

Thomas 0. Hodgins, B.E.S., M.A., R.P.P, Commissioner Development Services Department

MJS/ls/c Attachments

.. . March 2007 - IS- 06-1 113-171

6.0 SUMMARY AND CONCLUSIONS OF INVESTIGATION

1. The lowest pre-development elevation at the site of the Northwood Ridge Subdivision (approximately 163.5 masl) was at the west end of Clearsky Ave. and northwest end of Greenvalley Trail. Other than a small swale running in a south-westerly direction at the north end of the site, there were no defined pre-development surface water drainage features such as creeks on the site.

2. Post-development finished ground surfice elevations generally follow the original pre- development topography. Along Clearsky Ave., the postdevelopment elevations range fiom approximately 2.5 m higher than the original (pre-development) elevatio~s at the east end near Clearbrook Drive to less than 0.3 m higher than the original elevations at the west end near Wilson Road.

3. Sandy silt/silty sand till represents the primary soil stratum across the site. Some of the pre-development boreholes at the site encountered sand searnsllayers within the till deposit, mostly within 2 m depth below the pre-development ground surface. These sand searnshayers were reported by Soil Probe to be the prim& sources of groundwater at the site. The till deposit itself is a relatively low permeability material with an estimated in-situ hydraulic conductivity on the order of 1 x 10" cmls to 1 x lo6 cmls.

4. Groundwater level measurements taken on September 19,2006 and December 20,2006 at shallow monitoring wells located throughout the Northwood Ridge Subdivision indicate a groundwater surface approximately 1 m to 4 m below existing ground surface. The depth to groundwater along Clearsky Ave. increases in an easterly direction to as much as 3.7 m at the intersection of Clearsky Ave. and Clearbrook Drive. Comparison of groundwater levels for the shallow and deep monitoring wells along Clearsky Ave. indicates a predominantly downward hydraulic gradient ranging from 1% to 10%.

5. Groundwater surface contours based on September 19, 2006 and December 20, 2006 groundwater levels indicate a predominantly westerly groundwater flow direction towards Wilson Road. Along Clearsky Ave., the westerly direction of groundwater flow is essentially parallel to the street. There does. not appear to be any significant groundwater flow converging towards Clearsky Ave. from the north and south areas of the subdivision.

6. Comparison of the September 19 and December 20,2006 groundwater surface contours to the finished ground surface elevations for the subdivision, indicates several areas where the groundwater surface is within approximately 1 m of ground surface. These areas are shown on Figures 4 and 5 and include:

south-east end of Greenvalley Trail, Skyview Street and Clearbrook Drive, north of Blackwook Boulevard;

south-west end of Clearbrook Drive, north of Blackwood Boulevard; and

Golder Associates

21:

March 2007 - 16- 06-1 113-171

east end of Greenleaf Circle, adjacent the school area.

Lots within these areas may experience relatively persistent wet back yards during spring and fall seasons and should be further investigated to assess whether remedial work such as installation of sub-drain systems is required to depress the groundwater sutface.

7. A number of lots along Clearsky Ave. west of Skyview Street (shown on Figure 6), have foundation drains that are at or below the groundwater surface based on the September 19,2006 groundwater level measurements. Groundwater flow into footing drain systems for these lots is likely to be relatively persistent throughout most of the year. This condition exacerbates the build-up of calcium carbonate precipitate in the footing drain systems for these lots, as the rate of calcium carbonate build-up is directly propwtional to the rate and duration of groundwater inflow. The intersection of sand seamsllayers within the excavation depth of the foundations will further increase the rate of groundwater flow to the foundation drain and the build-up calcium carbonate.

8. The shallow groundwater wells installed to a maximum depth of 5 rn below finished ground surface along the boulevard of Clearsky Ave. and the shallow background (upgradient) well installed on the north side of Coldstream Drive near the park facility, indicate groundwater pH values in the 7.2 to 7.5 range and calcium concentrations in the 80 m a to 190 mg/L range. The groundwater at these wells is saturated with respect to calcium carbonate and will neither dissolve nor precipitate calcium carbonate unless its chemistry is altered, particularly its pH. An increase in the pH of the groundwater will result in reduced calcium carbonate mineral solubility and therefore precipitation of calcium carbonate from the groundwater. The pH of the groundwater can be increased by degassing of C02 from the groundwater on exposure to reduced COz partial pressure (e.g., to atmospheric C02 conditions) and/or by interaction with granular backfill materials.

9. It is considered that the crushing during production of a granular material such as the stone used beneath floor slabs and around footing drains can break down chemical bonds within the crystal lattice of mineral phases, which in turn can result in the formation of leachable oxides andlor hydroxides such as CaO and Ca(OH)2 on the broken partial surfaces. Dissolution of these oxideshydroxides when leached by groundwater can increase the groundwater pH. The broken chemical bonds and fiee oxidesihydroxides are likely to be more concentrated in the sand and fines fraction of the crushed product due to the higher specific surface area of this fraction. Therefore, the greater the sand and fines content of a crushed product, the greater will be the potential of the granular material to increase the pH of natural groundwater.

10. pH analyses of typical local granular materials (provided by the City fiorn various construction projects) indicate relatively high values for crushedlunwashed products such as Granular A (pH= 9.0), unwashed 19 mm clear stone (pH=8.6), crushed concrete (pH= 10-12) and crushed steel making slag (pH=12). Although not tested as part of this study,

Golder Associates

March 2007 . -

it is expected that other crushed/unwashed products such as limestone screenings and 19 rnm crusher run gravel have elevated pH levels as well. The greater the pH of the aggregate used beneath the floor slabs and around footing drains relative to that of the natural groundwater, the greater will be the potential for calcium carbonate precipitation within the footing drain system. Crushed/unwashed granular products have relatively high pH values compared to natural groundwater and should not be used in construction of foundation drain systems (including the gravel layer beneath the floor slab) particularly where the groundwater is saturated with respect to calcium carbonate and footing drains are below the seasonal high groundwater level.

1 1. A sample of typical washed 19 mm clear stone provided by the City gave a pH of 7.8, which is within the range of natural groundwater pH. Use of this type of product (i.e. washed uniform gravel) for foundation drain systems will reduce the potential extent of calcium carbonate precipitation.

12. The borehole investigation through the basement floor slab at four homes along Clearsky Ave. that experienced calcium carbonate formation, revealed that the gravel layer beneath the floor slab at each home consists of unwashed 19 mrn clear stone. There was no evidence of any crushed concrete or steel making slag. The pH of the gravel ranges b r n 8.58 to 9.78, which exceeds that obtained for the underlying native till (7.81-8.32) as well as that for groundwater at monitoring wells along Clearsky Avenue (7.19-7.53). The relatively high pH of the gravel indicates that it can raise the pH of the inflowing groundwater and therefore cause precipitation of calcium carbonate from the groundwater. The gravel sample that gave the highest pH (9.78) had the highest content of sand, silt and clay sizes (7%), whereas the sample that gave the lowest pH (8.58) had the lowest content of silt and clay sizes (0.5%). The cause of the elevated pH of the gravel is considered to be the presence of leachable oxides/hydroxides on broken surfaces of crushed particles. These oxideshydroxides are likely to be more concentrated in the sand, silt and clay size fraction due to the higher specific surfhce area of this fraction.

13. The primary cause of the calcium carbonate formation in foundation drain systems along Clearsky Avenue is likely to be interaction between the groundwater and the unwashed clear stone backfill used beneath the floor slab and likely around the perimeter footing drains. The unwashed gravel raises the groundwater pH, which in turn reduces its ability to maintain calcium and carbonate in solution. The rate of calcium carbonate build-up is exacerbated by footing drains being at or below the groundwater table throughout most of the year, particularly at some of the lots along Clearsky Ave west of Skyview Street.

14. Other lots that may be experiencing relatively persistent groundwater flow into the footing drain system and build-up of calcium carbonate, are located along the east side of Skyview Street and Clearbrook Drive near Blackwood Boulevard, as shown on Figures 6 and 7.

Golder Associates

2 2 ; )

March 2007

7.0 ALTERNATIVE APPROACHES FOR MITIGATION OF CALCIUM CARBONATE FORMATION

The following alternative approaches are provided for mitigation of the on-going calcium carbonate formation in the foundation drain system for homes along Clearsky Avenue and possibly for other the homes along Skyview Street and clearbrook Drive identified on Figures 6 and 7

1. Regular Cleaning of the Foundation Drain System

The least obstructive method of mitigating the calcium carbonate formation in the foundation drain system is to continue pressure flushing the FDC main and lateral connections to the homes on a regular basis to remove the calcium carbonate build-up before it hardens. The required frequency of cleaning will likely be at least twice per year (e.g., during spring and fall) for the next few years. It is expected that the required frequency will decrease with time as the soluble oxidesihydroxides in the gravel backfill, which are likely causing the pH increase of the groundwater and the calcium carbonate precipitation, are depleted. With time, the mechanism of any residual pH increase of the groundwater collected by the foundation drains will be by degassing of dissolved COz. This will occur mostly within the FDC main where there may be turbulent flow and aeration of the groundwater. The frequency of cleaning relating to this secondary mechanism of calcium carbonate formation will be much less (e.g., once every several years) or may not be required at all if turbulent flowlaeration in the FDC is minimal.

2. Lowering of the Groundwater Surface

Groundwater interceptor systems consisting of perforated pipe and washed natural (uncrushed) fine to medium sand backfill, can be installed along lot lines perpendicular to Clearsky Avenue to lower the groundwater level to below adjacent footing drains. The perforated pipe would be installed at least 1 m below the invert of adjacent footing drain pipes and ideally should extend the fir11 depth of the lot. The perforated pipe could discharge to a maintenance hole located on the boulevard, from which the groundwater would be pumped to the FDC main. This approach would reduce the groundwater flow rate to foundation drains and therefore minimize the rate of calcium carbonate build-up. Monitoring and cleaning of the FDC main, lateral connections and the groundwater interceptor system would still be required, but on a less frequent basis than for Alternative 1 (above). The primary problems with this approach are space limitations for construction equipment access and the need to obtain working easements.

Golder Associates

. March 2007 - 19- 06-1 113-171

3. Addition of Acidic Solution to the Foundation Drain System

An acidic solution could be continuously or intermittently added to the foundation drain system via the clean-outs, as a means of dissolving calcium carbonate deposits andlor maintaining the groundwater pH at a level that will not precipitate calcium carbonate. The selection of the type of acidic solution to use and the dose rate, requires special consideration of health and safety issues relating to chemical storagehandling, the variability in groundwater flow rate through the foundation drain system and the potential environmental impacts if excess amounts of acidic solution are added. Such an assessment would be very complex.

Of the three alternatives noted above, regular cleaning of the foundation drain systems is recommended at this time as this is the least obstructive, has been proven to work and has no significant health and safety or environmental issues. With time, the frequency of cleaning should decrease and eventually may not be required. The cleaning events should be preceeded by camera inspections to assess the degree of clogging and the appropriateness of the cleaning schedule.

8.0 CONSIDERATIONS FOR MINIMIZING CALCIUM CARBONATE CLOGGING OF FOUNDATION DRAINS IN FUTURE DEVELOPMENTS

Based on the findings of this study, it is recommended that the following be considered at the design stage of future residential developments, to minimize calcium carbonate clogging of foundation drains:

1. Chemical analyses should be carried out for groundwater within the depth of influence of the foundation drain system. The analyses should include field pH, alkalinity, iron, DOC and major anionslcations, to allow assessment of the state of saturation of the natural groundwater with respect to calcium carbonate. It is likely that most of the shallow groundwater in the Oshawa area is saturated with respect to calcium carbonate, given that the soils are predominantly derived from limestone. Such groundwater has the potential to precipitate calcium carbonate if, for example, the pH is increased due to interaction with alkaline granular backfill materials and/or due to degassing of COz on exposure to atmospheric conditions.

2. The depth of the footings below the seasonal high groundwater level should be minimized to the extent practicable, particularly where permeable strata are expected to be encountered within the excavation depth for the footings. This will minimize the rate of groundwater flow to the footing drain system and therefore will limit the rate of calcium carbonate build-up in the drain system.

Golder Associates

March 2007 - 20 - 06-1 113-171

3. Where there is a potential for calcium carbonate formation (e.g., groundwater is saturated with respect to calcium carbonate and footing drains are below the seasonal high groundwater level), use of washed 19 mm clear stone from a pit source is preferable for placement around footing drains and beneath the floor slab. Washed clear stone from a pit source rather than a quarry would have fewer crushed particles and therefore fewer broken surfaces with free oxidesihydroxides that can dissolve and elevate the groundwater pH. Crushed/unwashed products such as Granular A, crusher run sand and gravels, limestone screenings, crushed concrete, steel making slag and unwashed 19 mm clear stone should not be used beneath floor slabs and in the vicinity of footing drains.

4. The non-perforated connection pipe between the street line and the home foodng drain system should be increased in diameter to 150 mm (100 mm diameter pipe is currently being used). This will facilitate cleaning/inspection of the connection pipe and may reduce the required frequency of cleaning to remove calcium carbonate build-up within the connection pipe.

5. The FDC main should not have components (e.g., drop structures) which result in cascading and turbulence within the FDC main. This will reduce the potential for aeration of the groundwater within the FDC main and associated degassing of CQ from the groundwater. As described in this report, degassing of COz fmm the groundwater can increase the groundwater pH, which in turn can lead to calcium carbonate precipitation.

6. Although the above considerations aim at minimizing calcium carbonate build-up within foundation drains, it is recommended that visual inspection of the FDC main for calcium carbonate build-up should still be carried out at least once per year after a number of homes have been connected, until such time that the City assumes the subdivision. If excessive calcium carbonate build-up is evident, the lots contributing to the calcium carbonate build-up should be identified and associated FDC connection pipes as well as the FDC main regularly inspected and flushed to prevent blockage of flow and flooding of basements. The requirement for continued regular inspectionlcleaning of foundation drain systems for these lots as well as any other lots should be assessed prior to the City assuming the subdivision.

7. Although there may be maintenance issues (e.g., cleaning to remove calcium carbonate deposition), use of a separate FDC main for foundation drains rather than connection to the storm sewer is beneficial with respect to minimizing contamination and temperature increases of the collected groundwater prior to discharge to the receiving water course. Connection to a separate FDC main also removes the possibility of flooding of basements in the event of a storm sewer back-up during a major storm event. Ideally, the FDC main should discharge directly to the receiving water course rather than to a storm water pond, otherwise there may not be any environmental benefil.

Golder Assocfates

March 2007 -21 - 06-1 113-171

Although there may be maintenance issues (e.g., cleaning to remove calcium carbonate deposition), use of a separate FDC main for foundation drains rather than connection to the stonn sewer is beneficial with respect to minimizing contamination and temperature increases of the collected groundwater prior to discharge to the receiving water course. Connection to a separate FDC main also removes the possibility of flooding of basements in the event of a storm sewer back-up during a major storm event. Ideally, the FDC main should discharge directly to the receiving water course rather than to a storm water pond. otherwise there may not be any environmental benefit.

[n comparison. connection of the foundation drains to the stonn sewer has the advantage that dilution of the collected goundwater with stormwater will reduce the pH and prevent the build-up of calcium carbonate in the sewer. Unlike the FDC main; cleaning of the storm sewer for calcium carbonate would not likely be required. However. calcium carbonate clogging of the individual footing drain connector pipes to the homes can still occur.

COLDER ASSOCIATES LTD.

Frank S. Barone, Ph. D., P. Eng. Associate

Golder Associates

TOTAL P.007


Councillor Jdm Neal ward 7 City and Regional Councillor 50 Centre St. S.

ElH 327

Dear Mr. Neal:

f talked to you on March f 0,2006 abut my house. It is a thee year ~ l d house and it ha a big

problem sincs it was built. The prc'otem if. drat my basement gets floated couple titnes a year

b e a w e the howe was built in !he arm that has e x p a r i d a calcium carbonate build-up that has

restricted ?he flow of water tiom armd the foundation. Since the time I a e d to you nothing has

cbqed or done abw: it, f would like to klow what C i i of Orhawa is going to do to fix the

problem and w h a the pmblan cao be tixed Taioo Wamnty Corpcrmtioo can not do mything

abut it becaw thq, wy that it is a City of Oshawa pr~bkn~. Can you picase help me with this \

-- problem.

RECEIVED

d.OL ?&:Rw&ORS' OW##= GITX OF O w -

0. G. Biddle & Associates Limited c o n s u l t i n g e n g i n e e r s 96 KING ST. E.. OSHAWA. ONTARIO UH lB6 PHONE

e-mall: dgblddleOldlrect.com R E C E I V E D

I July 25,2002

The Corporation of the City of Oshawa Department of Development and Planning Services Building Department 50 Centre Street South Oshawa, Ontario LIH 327

Attention: - Mr. Andre O'B~lrnswah

Re: H. Kassinger Construction Limited Northwood Ridge Subdivision - Phase 2 Draft Plan 18T-95025; 40M-1963 Schedule 'D' Condition 25 Our File: 98052

Dear Sir:

We have been retained by H. Kassinger Construction Limited in accordance with Clause 25 of S~Aeduie '3 of tine above Subdivision Agreement to sanf~m that baselnent s!ah ai; above the local water table.

A second part of Clause 25 of Schedule 'D' addresses soil gas concentration. It is our understanding that the soil gas (radon) concentration issue has been addressed previously for all development in Oshawa and that the City is satisfied that this is no inngsr an issue.

As Engineer's for the subdivider, our staff provided resident inspection of the urldergraund services during construction and consequently have good knowledge of the site. The sanitaly and foundation drainage sewers servicing the dwellings are all below the level of the basement floor and generally will intercept ground water flows.

Regarding the dwellings that have been constructed to date, we understand that no water has been encountered above the floor slab that could not be managed by the under floor stone drainage and weeping tile systems.

- - - .- -- .---- _ _ _ _ . _ - . _ _ _ _ _ _ I I __ -----I --------- -- .- - --- ----- -- - a

-- - - . - - -- - - - - --.---TI-- - - - conventional weeping tile system and damp proofing solutions. We will inspect any ground water levels or Rows encountered in the basement excavations as they proceed to ensure that adequate damp proofing or water proofing systems are provided.

Please contact the author if you have any questions regarding the above information.

Yours truly,

D.G. BIDDLE & ASSOCIATES LIMITED

R.M. Larocqyo; P :-Wg. RMVbms LeWese

c.c. Mr. J. Bathe, H. Kassinger Construction ~ i k t e d c\9B052\sch'd'.wpG

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